1. Field of the Invention
The present invention relates to a covered airtight container made of plastics for packing and selling processed foodstuffs such as fishes, shellfishes and edible wild plant, etc.
2. Prior Art
There has been widely employed a covered airtight container comprising a body made of hard material and a cover made of flexible material in which the body has a projection at an upper end outer peripheral surface of a peripheral wall and the covet- has an edge portion piece formed by bending the upper end edge thereof upward and reversing it downward for engaging with the upper end portion of the peripheral wall of the body. The cover also has and an annular groove at the inner peripheral surface of the edge portion piece for engaging in the projection of the body. In such a prior art covered airtight container, the sealing state of the cover is stable if the projection of the body is triangular in cross section to Form a clearance angle at the lower portion. However, the edge portion piece of the cover must be cut off along the annular groove since the cover can not be removed from the body as it is. As illustrated in FIG. 1, a notched window 29 is provided at a part of the edge portion piece 17. A cutoff device 4 comprises a knob 31 which is provided on the lower end portion 17A of the edge portion piece 17 and disposed at the lower end portion of the notched window 29. The knob 31 projects from one end of the lower end portion of the notched portion 29 and connects to the other end thereof at a point connection 33. If the knob 31 is pulled out and cut off at the point connection 33, the lower end portion 17A of the edge portion piece 17 can be pulled off.
An advantage of such a prior art covered airtight container, there is that soup does not leak from the container because of the airtight connection between the projection of the body and the groove of the cover and the cover does not come off until it is opened. However, the disadvantage is that there is a possibility that the soup leaks when the body is thermally expanded or shocked during its conveyance because the body and the cover are connected by a single projection and groove. Particularly, when the cover is open, namely, the body is uncovered, the soup is liable to leak because of there is no connection between the annular projection and the annular groove. This is true even if the cover is closed, namely, the body is covered by the cover.